Kindly we need to maintain budgeting on GL level and asset code and material ( without link any cost center or WBS ).
Both Budgeting and Planning of expense items require assignment to a Cost Object to both load and report against, so either CC or WBS needed. You could create a "planning" CC or WBS to support this requirement. Whilst Asset and Material are not listed as Fields for Financial Plan Data Import they do exist in the Planning table (ACDOCP). You can add fields ANLN1 (main Asset), ANLN1 (subnumber) and MATNR (material) to the Planning import templates.
Note that you may need to include these fields on the Plan data display apps (for example MATNR is available in Financial Plan Data app but Asset is not).